Monitoring Earth's Climate from Space
"These measurements are designed to decisively answer several basic questions about climate, including how the thermodynamic structure of our atmosphere is changing and what processes are at work," UA atmospheric scientist and project leader E. Robert Kursinski said.
The researchers will flight-test the prototype device on two high-altitude jets less than three years from now.
The proposed system is designed to give global climate change scientists benchmark data that is critically needed for research and policymaking. If successful, its impact would be huge, National Science Foundation proposal reviewers said. No such global climate observing system exists and is a high priority for monitoring climate, the National Research Council said in its latest decadal survey.
Kursinski and his team, which includes researchers from the Steward Observatory Radio Astronomy Laboratory, won a 3-year, $1.6 million National Science Foundation Major Research Instrumentation grant to construct and demonstrate the prototype instrument. The Jet Propulsion Laboratory in Pasadena, Calif., Aerospace Corp. in El Segundo, Calif., and the Southern Research Institute in Birmingham, Ala., are partners in the project.
The instrument is a spectrometer that would probe Earth's atmosphere at microwave frequencies using "active" radio occultation techniques. One aircraft will carry a transmitter that sends a microwave signal through the atmosphere. A second aircraft will carry a receiver that picks up the signal after it has recorded the effects of the atmosphere. The instrument will be tested in aircraft-to-aircraft occultations to demonstrate its feasibility for satellites. It is called the Active Temperature, Ozone, and Moisture Microwave Spectrometer, or ATOMMS.
Plans call for mounting the instrument in the nose cones of two WB-57F high-altitude jets that NASA developed to photograph damage to Space Shuttle tiles. The aircraft would be flown toward one another at about 19 kilometers (about 12 miles) altitude from positions over the horizon for observations that will profile atmospheric temperature, water vapor and ozone down through the troposphere below. NASA will provide the aircraft support for the demonstration.
Kursinski and his colleagues have developed their concept for measuring climates both on Earth and on Mars, but they will demonstrate it first for Earth.
"A couple of things are different about this remote sensing system," Kursinski said. "One, Earth is a cloudy planet. About 60 to 70 percent of the globe is covered by clouds. Unlike any other sensors flying right now, radio occultations can characterize the atmosphere in and below clouds.
"The second difference is that present state-of-the-art sensors are limited to measuring water vapor at 2-kilometer vertical increments (about 1.25 miles), or about six levels across the troposphere, which is about 12 kilometers high (7.5 miles). Water vapor varies vertically over much finer scales than that.
"Our instrument will resolve water vapor at 200 meters (about 660 feet) vertically in the atmosphere, or 10 times better than the best there is now. It will nail the vertical structure of water at the upper troposphere-lower stratosphere, which is very important," Kursinski said. "Although there's relatively little water at these higher altitudes compared to how much water is near Earth's surface, water in the upper troposphere-lower stratosphere exerts a strong greenhouse effect because it's so cold up there."